The Biospecimen and Pathology Core ofthe Breast SPORE is responsible for accessioning and processing new biospecimens for the Breast SPORE Biospecimen Repository and to make those specimens available for use in the four SPORE main projects and very likely for the Developmental Research and Career Development Programs. Biospecimens will also be made available to other intra- and extra-mural investigators engaged in breast cancer translational research. Requests for biospecimens will be taken under consideration by the Breast SPORE Operations Committee, with a heavy emphasis on scientific merit and on availability of specimens and their associated data needed for analysis. Input from the Biostatistics and Patient Registry Core is included in the evaluation of requests for tissues. The Pathology Team of the Biospecimen Core will provide detailed annotations in the Breast Pathology Database for frozen and formalin-fixed paraffin-embedded tissues from selected cohorts of patients to support SPORE projects and additional projects for which the Breast Biospecimen Repository has provided tissues. The Core pathology team will also interpret IHC staining. The Biospecimen and Pathology Core will coordinate with the Mayo Clinic Cancer Center Biospecimen Accessioning and Processing Shared Resource to process blood samples to provide genomic DNA and serum aliquots, and with the Tissue and Cell Molecular Analysis Shared Resource to provide histology and other tissue-based services, including paraffin and frozen sectioning, immunohistochemistry, tissue microarray construction, and digital imaging. Working closely with existing infrastructure such as these shared resources minimizes redundancy of services and utilizes existing experience and state ofthe art equipment. New immunostaining assays will be developed by the Biospecimen and Pathology Core, as well as construction of cell line tissue microarrays to screen and test antibodies for immunostaining formalin-fixed, paraffin-embedded tissues.